Japanese Journal of Applied Physics, 22 (1983), Supplement, 22-2, pp. 3 to 7, discloses a process for producing barium titanates by a sol-gel process in which tetraisopropoxytitanium is admixed with barium metal in the presence of acetylacetone, acetic acid and isopropyl alcohol. This process poses, however, problems in that barium metal which is difficult to handle is used and that it is not easy to set optimum conditions because of a variety of organic solvents used.
Ceramic Bulletin, 55 (1976) pp 1064 to 1065, discloses a process for producing barium titanates by a sol-gel process in which a titanium alkoxide is admixed with barium naphthenate in butanol. However, this process involves problems in that the barium naphthenate because of its large molecular skeleton and molecular weight requires quantities of heat when calcined and that the barium titanates obtained by this process have a large percent shrinkage and are liable to be cracked.
Journal of Materials Science, 20 (1985) pp 4479 to 4483, discloses a process for producing lead titanates by a sol-gel process in which tetraisopropoxytitanium is admixed with lead acetate in ethylene glycol monomethyl ether and in which nitric acid is used as a catalyst for the hydrolysis. This article is, however, completely silent with respect to barium titanates. Further, because of the fact that while lead acetate is soluble in ethylene glycol monomethyl ether, barium acetate is insoluble in this solvent, a person skilled in the art would not conceive to apply the process of the article to the preparation of barium titanates.